What You Should Know About Contrast Dyes Used in Medical Imaging

Contrast agents, medical imaging contrast, and contrast materials. These are suitable names for the contrast dye that’s used in medical imaging. You may be starting to explore what contrast dyes after you’ve been referred for an X-ray with contrast or a CT scan with contrast, and you might see many of these names in the journals and articles you need.

Here at Excel Diagnostics & Nuclear Oncology Center, Dr. Ebrahim Delpassand and our team offer contrast radiography services, including positron emission tomography (PET) scan and computed tomography (CT) scan (PET/CT). While we use these images to reach accurate diagnoses of a wide range of medical conditions affecting the blood vessels or organs, you might wonder what contrast dyes are or why they are so frequently used as part of diagnostic testing for cancer.

Here’s what you need to know.

What is contrast dye?

Regardless of which nomenclature you use, all contrast dyes have a common purpose: to help radiologists visualize your organs and tissues more clearly in your medical images. Although it doesn’t physically change the color of your organ, it’s called a dye because it changes how your insides appear on a medical image, such as a CT scan, while the dye is still in your system.

There are different types of dye, depending on which type of imaging test you need. Gadolinium contrast, for example, can be used during an MRI, while iodinated contrast is used for X-ray-based imaging tests. Depending on which type of dye you need, you either swallow the dye in drink form, or it’s injected into one of your veins. 

Let’s take a look at how contrast dye works. The dyes interfere with how medical imaging equipment, such as X-ray machines or CT machines, work. Iodinated contrast dye, for instance, blocks radiation to certain parts of your body. This changes how the X-ray machine sees your bones or organs. Just like how your bones show up clearly on X-rays (because the X-rays don’t pass through them easily), the contrast material blocks the X-rays in your blood vessels and organs, which makes them show up more clearly on the X-ray ー just like how your bones normally do on an X-ray.

How does contrast dye improve medical imaging?

The dye doesn’t change or alter any of your tissue, but it improves how the imaging technology ー whether that’s a CT, MRI, or X-ray ー sees your organs and blood vessels. Contrast dyes help to sharpen the contrasts between your organs, tissues, bones, or blood vessels. 

When our team can better visualize your soft tissue structures, it’s easier to distinguish abnormalities, such as cancer metastasis. In turn, this leads to more accurate diagnoses and better treatment plans tailored to your specific condition. 

Ultimately, contrast dye leads to better care. 

Who needs medical imaging with contrast?

You might need an X-ray, CT, MRI, or ultrasound exam with contrast to:

• Confirm a diagnosis
• Determine the location and extent of cancer
• Monitor your response to cancer treatments
• Identify any metastases 

Preparing for a medical imaging test with contrast varies depending on which type of test you need and what type of dye you will receive. You can expect that a test with dye lasts anywhere from two to four hours, allowing for plenty of time for the dye to reach the specified areas.

When you are preparing for a medical imaging test with contrast dye, rest assured that our compassionate and expert team prepares you for every step of the test. Before your test, let our team know if you’ve had previous allergic reactions to contrast dye, what medications you’re currently taking, if you have a history of asthma, and any other underlying health conditions you have. If you have had an allergy to contrast dyes in the past, our team may recommend an allergy protocol, which can include steroids and diphenhydramine prior to your test. Because the images produced with dye are so invaluable, we want to do everything we can to ensure your tests run smoothly.

 If you have any questions, don’t hesitate to reach out. 

What happens after a medical imaging test with contrast dye?

After your imaging test, your body will either absorb or eliminate the contrast agent through a bowel movement. 

To learn more about contrast dyes used in medical imaging, or to schedule an appointment, call our Houston, Texas, office at 713-781-6200. You can also schedule appointments online.